Feeding the fire: Tracing the mass-loading of 10^7 K galactic outflows with O VI absorption

Galactic outflows regulate the amount of gas galaxies convert into stars. However, it is difficult to measure the mass outflows remove because they span a large range of temperatures and phases. Here, we study the rest-frame ultraviolet spectrum of a lensed galaxy at z~2.9 with prominent interstellar absorption lines from O I, tracing neutral gas, up to O VI, tracing transitional phase gas. The O VI profile mimics weak low-ionization profiles at low velocities, and strong saturated profiles at high velocities. These trends indicate that O VI gas is co-spatial with the low-ionization gas. Further, at velocities blueward of -200 km/s the column density of the low-ionization outflow rapidly drops while the O VI column density rises, suggesting that O VI is created as the low-ionization gas is destroyed. Photoionization models do not reproduce the observed O VI, but adequately match the low-ionization gas, indicating that the phases have different formation mechanisms. Photoionized outflows are more massive than O VI outflows for most of the observed velocities, although the O VI mass outflow rate exceeds the photoionized outflow at velocities above the galaxy's escape velocity. Therefore, most gas capable of escaping the galaxy is in a hot outflow phase. We suggest that the O VI absorption is a temporary by-product of conduction transferring mass from the photoionized phase to an unobserved hot wind, and discuss how this mass-loading impacts the observed circum-galactic medium.Comment: 17 pages, 12 figures, accepted for publication in MNRA

Numerical Study of Three-dimensional Spatial Instability of a Supersonic Flat Plate Boundary Layer

The behavior of spatially growing three-dimensional waves in a supersonic boundary layer was studied numerically by solving the complete Navier-Stokes equations. Satisfactory comparison with linear parallel and non-parallel stability theories, and experiment are obtained when a small amplitude inflow disturbance is used. The three-dimensional unsteady Navier-Stokes equations are solved by a finite difference method which is fourth-order and second-order accurate in the convection and viscous terms respectively, and second-order accurate in time. Spanwise periodicity is assumed. The inflow disturbance is composed of eigenfunctions from linear stability theory. By increasing the amplitude of the inflow disturbance, nonlinear effects in the form of a relaxation type oscillation of the time signal of rho(u) are observed

When seeing is more than looking:Intentional gaze modulates object desirability

Objects in the environment have a perceived value that can be changed through social influence. A subtle way to influence object evaluation is through eye gaze: Objects looked at by others are perceived as more likable than objects that are not looked at. In 3 experiments, we directly tested the hypothesis that this liking effect depends on the processing of the intentional relation between other's eye gaze and the object being looked at. To this end, we used a novel paradigm in which participants observed a face looking left or right behind an opaque barrier. Under all tested conditions, we found a gaze cueing effect on attention: Looked-at objects were categorized faster than looked-away objects. In contrast, observed gaze only led to a boost in affective evaluation for the target object when observers had the impression that the face could see the object behind the barrier, but not when observers had the impression that the face could not see the object. These findings indicate that observers make a sophisticated use of social gaze cues in the affective evaluation of objects: Objects looked at by others are liked more than objects looked away but only when others can see the objects

A perceived gap between invasive species research and stakeholder priorities

Information from research has an important role to play in shaping policy and management responses to biological invasions but concern has been raised that research focuses more on furthering knowledge than on delivering practical solutions. We collated 449 priority areas for science and management from 160 stakeholders including practitioners, researchers and policy makers or advisors working with invasive species, and then compared them to the topics of 789 papers published in eight journals over the same time period (2009–2010). Whilst research papers addressed most of the priority areas identified by stakeholders, there was a difference in geographic and biological scales between the two, with individual studies addressing multiple priority areas but focusing on specific species and locations. We hypothesise that this difference in focal scales, combined with a lack of literature relating directly to management, contributes to the perception that invasive species research is not sufficiently geared towards delivering practical solutions. By emphasising the practical applications of applied research, and ensuring that pure research is translated or synthesised so that the implications are better understood, both the management of invasive species and the theoretical science of invasion biology can be enhanced

Examining the broadband emission spectrum of WASP-19b: A new z band eclipse detection

WASP-19b is one of the most irradiated hot-Jupiters known. Its secondary eclipse is the deepest of all transiting planets, and has been measured in multiple optical and infrared bands. We obtained a z band eclipse observation, with measured depth of 0.080 +/- 0.029 %, using the 2m Faulkes Telescope South, that is consistent with the results of previous observations. We combine our measurement of the z band eclipse with previous observations to explore atmosphere models of WASP-19b that are consistent with the its broadband spectrum. We use the VSTAR radiative transfer code to examine the effect of varying pressure-temperature profiles and C/O abundance ratios on the emission spectrum of the planet. We find models with super-solar carbon enrichment best match the observations, consistent with previous model retrieval studies. We also include upper atmosphere haze as another dimension in the interpretation of exoplanet emission spectra, and find that particles <0.5 micron in size are unlikely to be present in WASP-19b.Comment: 10 pages, 8 figures, 2 tables, accepted for publication in Ap

Boundary layer transition

The boundary layer stability, its active control by sound and surface heating and the effect of curvature are studied numerically and experimentally for subsonic flow. In addition, the experimental and flight test data are correlated using the stability theory for supersonic Mach numbers. Active transition fixing and feedback control of boundary layer by sound interactions are experimentally investigated at low speed over an airfoil. Numerical simulation of active control by surface heating and cooling in air shows that by appropriate phase adjustment a reduction in the level of perturbation can be obtained. This simulation is based on the solution of two-dimensional compressible Navier-Stokes equations for a flat plate. Goertler vortices are studied experimentally on an airfoil in the Low Turbulence Pressure Tunnel (LTPT). The flow pattern was visualized using the sublimating chemical technique and data were obtained using a three component laser velocimeter. The effect of curvature on swept leading-edge stability on a cylinder was numerically studied. The results suggest that transition is dominated by traveling disturbance waves and that the waves with the greatest total amplification has an amplitude ratio of e sup 11. Experimental data from the quiet supersonic tunnel and flight tests are analyzed using linear compressible stability theory

SuperLupus: A Deep, Long Duration Transit Survey

SuperLupus is a deep transit survey monitoring a Galactic Plane field in the Southern hemisphere. The project is building on the successful Lupus Survey, and will double the number of images of the field from 1700 to 3400, making it one of the longest duration deep transit surveys. The immediate motivation for this expansion is to search for longer period transiting planets (5-8 days) and smaller radii planets. It will also provide near complete recovery for the shorter period planets (1-3 days). In March, April, and May 2008 we obtained the new images and work is currently in progress reducing these new data.Comment: 3 pages, 2 figures, to appear in the Proceedings of IAU Symposium 253, 2008: Transiting Planet

Episodic disk accretion in the halo of the 'old' Pre-Main Sequence cluster Eta Chamaeleontis

We present multi-epoch medium-resolution observations of two M4.5 candidate members in the halo of the ~8 Myr Eta Chamaeleontis open cluster. Over six months of observations both stars exhibited variations in their H-alpha line profiles on timescales of days to months, with at least one episode of substantial activity attributable to accretion from a circumstellar disk. We derive an accretion rate ~10^-8.7 Msun/yr for this event, with a rate of ~10^-10.6 Msun/yr in quiescence. Episodic accretion like that observed here means existing surveys of accreting Weak-lined T-Tauri Stars in young clusters are likely incomplete and that gas dissipation timescales calculated from the fraction of accreting objects are underestimates.Comment: 5 pages, 5 figures, 1 table. Accepted for publication in MNRAS Letter

Probing Individual Star Forming Regions Within Strongly Lensed Galaxies at z > 1

Star formation occurs on physical scales corresponding to individual star forming regions, typically of order ~100 parsecs in size, but current observational facilities cannot resolve these scales within field galaxies beyond the local universe. However, the magnification from strong gravitational lensing allows us to measure the properties of these discrete star forming regions within galaxies in the distant universe. New results from multi-wavelength spectroscopic studies of a sample of extremely bright, highly magnified lensed galaxies are revealing the complexity of star formation on sub-galaxy scales during the era of peak star formation in the universe. We find a wide range of properties in the rest-frame UV spectra of individual galaxies, as well as in spectra that originate from different star forming regions within the same galaxy. Large variations in the strengths and velocity structure of Lyman-alpha and strong P Cygni lines such as C IV, and MgII provide new insights into the astrophysical relationships between extremely massive stars, the elemental abundances and physical properties of the nebular gas those stars ionize, and the galactic-scale outflows they power.Comment: 4 pages, 3 figures. To be published in the Proceedings of IAU Symposium 309. For more details and closely related work see also arXiv:1310.6695 and arXiv:1406.335